THE FAMILIES AND GENERA OF BATS. 
171 
specialized. In the reduction of the rostrum Sphceronyeteris has 
certainly proceeded further ; this is also true of the plate-like develop- 
ment of the anterior edge of orbits and of the widening and upward 
bending of the zygomata. On the other hand the persistence of the 
third lower molar is a more primitive character, the form of the 
upper canine and of the palate is less aberrant, and the development 
of the dermal outgrowths on face is much less extreme. 
Genus AMETRIDA Gray. 
1847. Ametrida Gray, Proc. Zool. Soc. London, p. 15. 
1878. Ametrida, Dobson, Catal. Chiropt. Brit. Mus., p. 530. 
Type- species. — Ametrida centurio Gray. 
Geographic distribution. — Tropical South America. 
Number of forms. — -Two species are now known. 
Characters. — Differs from Sphceronyeteris in the presence of a 
> small but normally formed noseleaf , in the still greater shortening of 
the rostrum, so that flat space in front of nares is wider than distance 
between canines, in the retraction of the anterior wall of orbit until 
orbital space is wider than long, in the presence of a mere bead along 
anterior rim of orbit, and in the practical absence of any interptery- 
goid space, the pterygoids being directed almost perpendicularly out- 
ward and the choanse opening between them as a rounded vertical 
aperture facing backward. Teeth essentially as in Sphceronyeteris , 
but upper incisors smaller and inner cusps of upper molars better 
developed, though in the same position. Minute third lower molar 
present as in Sphceronyeteris. 
Species examined. — Ametrida centurio Gray and A. minor H. Allen. 
Remarks. — Of the three related genera, Ametrida , Sphceronyeteris , 
and Centurio , the first is externally the least modified, retaining as it 
does its practically normal noseleaf. In dental characters it agrees 
with Sphceronyeteris , which is in this respect less aberrant than 
Centurio. Its skull, however, is the most peculiar of the three, show- 
ing the greatest extreme of rostral shortening, and in addition having 
a structure of the choanae that is unique among bats. 
SuL.ram.il5r PHYLLOXYCTERIXJ]. 
1865. Glossophagce (part) Peters, Monatsber. k. preuss. Akad. Wissensch., 
Berlin, p. 257. 
1875. Glossophagce (part) Dobson, Ann. and Mag. Nat. Hist., 4tli ser., XVI, 
p. 350, November, 1875. 
1878. Glossophagce (part) Dobson, Catal. Chiropt. Brit. Mus., p. 497. 
1886. Glossophagince (part) Gill, Standard Natural History, V, p. 173. 
1891. Phyllostomatince (part; Glossopkagine division, part) Flower and 
Lydekker, Mammals, living and extinct, p. 672. 
1892. Glossophagce (part) Winge, Jordfundne og nulevende Flagennus 
(Ckiroptera) fra Lagoa Santa, Minas Geraes, Brasilien, p. 24. 
1898. Brachyphyllina (part) H. Allen, Trans. Amer. Philos. Soc., n. s., XIX. 
p. 258. 
